Today aerodynamic surfaces of airborne vehicles, such as type wing skins, fin skins, control surfaces, wind turbine blades, open rotor blades etc., having aerodynamic functions, are protected from icing by means of anti-icing/de-icing devices arranged in the aerodynamic surface. Icing is known as an undesired phenomenon, where a build-up of ice is taking place on the aerodynamic surface (outer surface of the article). The aerodynamic surface could also be comprised in engine air intakes, inlet channels etc.
This has been successful for articles with skins made of metal, such as aluminium, as the heating element can be placed under the skin and the heat will be transferred through the metal skin, due to the good conductive property of the metal, and the ice will melt.
Today, however, articles with aerodynamic surfaces are more often made of matrix composite reinforced by for example carbon fibres in the plane of the laminate, but oriented in different directions parallel with the plane of the laminate. The laminate resin has not satisfying thermal conductivity properties and when the heating element is heated for melting the ice on the outer surface of the skin, often the whole skin has to be heated before any ice will be melt. This is thus not beneficial, since the thermal losses provide that the energy consumption will be far too high resulting in a non-economic fuel consumption of the aircraft which also not is environmental-friendly.
The aerodynamic surface is herein defined as the outer (wet) surface of article moving through the air. The article is preferably a component of an airborne vehicle, wherein the article structure comprises a resin matrix made of a lay-up of plies, each ply comprises fibres having an orientation different from the fibre orientation of an adjacent ply, wherein the structural article comprises said outer surface.
US 2005/0189345 discloses strips of composite substrate having resistor elements of electrically-conductive fibres, which elements are arranged under a metal shielding forming the skin surface of the aerodynamic surface.
Today, research and development efforts are present within the aircraft industry to produce more environmental friendly aircrafts. One solution is to develop the aircraft's power plants so that they are more efficient requiring less fuel. Another way is to save weight of the structural parts of the aircraft, whereby the fuel consumption can be reduced.
Nano structures (such as nano fibres/tubes in polymeric materials) are more often used in different applications in aerospace industry in recent years. This is due to the high strength and stiffness of the nano fibres/tubes embedded in the polymeric material, often together with a fibre matrix of carbon or graphite fibres, within the material.
US 2009/0140098 discloses an aircraft component having a resin matrix including carbon nano tubes embedded therein for providing high conductivity of the component in order to defrost the latter.
A purpose of the present invention is thus to provide an matrix composite laminate having a de-icing/anti-icing function, which laminate effective concentrate the thermal heat generated by a heating element of the article in an optimal way reducing thermal losses, thus saving energy of an aircraft's energy supply.
A further purpose is to provide strength to the laminate also in a direction transverse to the extension of the laminate (z-direction).
It is also desirable in an effective manner to provide and maintain the smoothness of the article's outer surface of the laminate during the manufacture of the article. It is also desirable to maintain the smoothness of the outer surface during the service and/or flight of the aircraft. It would thus be beneficial for the aerodynamic efficiency of the article if the outer surface were smooth during the whole service life, thereby promoting a reduced fuel consumption of the aircraft and achieving a cost-effective and environmental friendly transportation of people and goods.
A further object is also to eliminate the eventual drawbacks of known techniques.